Setting up Cam Sync completely from nothing

[Sprocket]

I am going to install a Cam Sync sensor on my engine. The sensor and trigger are sorted as Im using what was an original VR set up on the Late A seires engine.

However, as the trigger is part of what used to be the camshaft, on this engine, that cam now only drives the oil pump with ALL the cam lobes machined off, just leaving the cam sync trigger.

What I need to know is where to set the cam sync trigger in relation to the engine cycle.

This is a complete and fully adjustabe set up so I am open to suggestions.

Thanks

[GintsK]

I always try to put cam signal just before missing teeth in compression stroke of 1st cylinder. It reset firing order table in usual position. And gives fast sync at cranking.

Gints

[Sprocket]

Ok so I an now getting close to setting this up. Head will be going on the engine next week and cams timed in, so I need to know where to set up the cam sync sensor.

I can locate the secondary trigger at 10 degree intervals (number of teeth on the drive gear). I have marked up the drive gear to indicate a dead center position of the trigger lobes in relation to the sensor. Obviously there is a rising edge and falling edge, but for ease of setting up, I marked it at its center alignment.

I intend to set the crank angle at X degrees BTDC then align the marks for the secondary trigger, but what sort of crank angle are we talking about? The primary trigger will be set for 90 degrees BTDC, so going off what Gints says above, I should be looking at something like 120 degrees BTDC?

any advice welcome

Here's a pic of the secondary VR trigger on the jackshaft (the camshaft without lobes )

[rob@vems.co.uk]

Go for 120deg BTDC and use 25 as the raw setting.
Be on the lookout for VR noise - it can easily cause a mis-trigger on a secondary/cam sync setup.

[Sprocket]

Thanks Rob.

I'll be using industrial grade screen cable, with the screen grounded at the common ground, plus the sensor is round the back of the engine away from noisey electrical equipment. I would prefer to use a Hall sensor, but its finding one that would fit the hole in the block. I think I should be OK as I dont think I had any issues with noise on the primary trigger with the same cable.

One other thing, looking at the settings in Vemstune, the raw setting I can no longer modify, but you can see it change as the different settings are manipulated. 25 looking like a basic VR cam sync set up. But, what about filtering? there is an option for filtering and when enabled, the raw setting is 29. Do I leave filtering off, or will I benefit from having it on with the VR sensor?

[rob@vems.co.uk]

Leave filtering off, it does something with stuff and is a complete undocumented unknown type of thing.
You may want to try some pull-up and pull-down resistors to filter out any of the unpleasant noises.

[Sprocket]

I'll keep that in mind, but for now, I will give it a go without. I intend to get the engine run in first on Dual Out mode with everything in place to go full sequencial when Im happy with the new engine and firmware. I suppose I could log the secondary trigger and monitor it for any noise. Any ideas how I might do that?

[rob@vems.co.uk]

Mr Scope will tell you all you need to know.

[Sprocket]

Topic resurection Has it really been that long

Back the discussion of whee to set the secondary trigger. Settings have changed somewhat since I discussed this last, or maybe it's just my memory lol.

One thing I'd like to go over again, where to set the secondary trigger in relation to engine cycle and primary trigger. As I understand it, secondarly trigger occurs before primary trigger when cylinder 1 is on the compession stroke? so for example, cylinder 1 on compression stroke (engine cycle 180 to 360 degrees), secondary trigger occurs at say 30 degrees prior to pimary trigger which occurs at 90BTDC?

Is 30 degrees between secondary and primary trigger to much, too little, or about right?


So now looking at the settings in 1.1.98.

Leaving sectrig min and max values at 1/ 360 defaults with 'Justshow'

'ignore sectrig pulses above' set to 255 default?
This would ignore any secondary trigger pulses after 255 degrees?

'LS1 forgiving' I have no idea?
'Maximum primary edge between secondary edges' I have no idea?


Insimple terms, what should I set crank angle to (BTDC) and have secondary tigger lined up, and is this on the compression or exhaust stroke. I here people talking about faster sync by swapping round the trigger refference table, so I supose it doesnt really matter, as its easy enough to change the refference tables.


Timing belt will be going on the engine tomorrow evening so Any help is appreciated, Thanks.

[GintsK]

In simple - anywhere except missing gap. IMO more comfortable so (in historical sequence): camsignal (anywhere) ->missing gap->spark in 1st cylinder.
additional settings allow to use various more complicated trigger patterns.